Tetramethylpyrazine, an active constituent found in the rhizome of Ligusticum chuanxiong Hort, possesses anti-platelet,anti-atherosclerosis, anti-thrombus synthsis, emphysema prevention, anti-pulmonary edema, anticoagulant, antitumor,and antioxidation effect. In this study, the pharmacokinetics of tetramethylpyrazine in rabbits were evaluated. A simple high performance liquid chromatographic method involving UV detection was modified for determination of tetramethylpyrazine in rabbits plasma. A Merck LiChrospher 100 RP-18e (250×4 mm) column was used as the stationary phase and mobile phase of methanol:water(50:50) and flow rate at 1.0 ml/min, and 7-hydroxycoumarin solution as the internal standard. The UV absorbance was monitored 280nm. The limit of quantitation was 0.05 μg/ml, recovery was 94 %. The coefficient for intraday and interday precison and accuracy was less 10 %. Their data inducates this modified method was enough for a quantitative analysis of tetramethylpyrazine. The pharmacokinetics of tetramethylpyrazine in the rabbit after intravenous bolus administration of various doses (20、40mg/kg) were well described by two compartment open model. The elimination half-lives were 36.9±2.4 and 38.6±7.6 min,respectirely；mean volume of distribution were 14.400±1.474 and 17.286±1.447 L,respectirely；the area under the plasma level-time curve were about 238.988 ± 36.633 and 403.056± 53.573μg．min/ml. ,respectirely The pharmacokinetics of tetramethylpyrazine after oral administration (50mg/kg) to rabbits also exmined. The mean area under the serum concertration curve (AUC) were 201.325±83.25μg．min/ml. The mean half-life (T1/2) were 142.4 min.The oral bioavailability was about 40 %. These result may be useful in support of the dosage forms design and provide to general use information.
